CLEVELAND, Ohio - After a decade of imprisonment, Amanda Berry suddenly realized there was the opportunity to escape from Ariel Castro's Seymour Avenue home. She recalls that moment for ABC News anchor Robin Roberts during an interview that will air at 10 p.m. Tuesday, April 28, on WEWS Channel 5.

It was May 6, 2013, and Berry noticed that Castro wasn't home.

"I didn't know what to do," Berry tells Roberts in interview excerpts released by ABC News. "My heart immediately started pounding, because I'm like, 'Is - should I chance it? He could be here any minute. If I'm going to do it, I need to do it now.'"

A special edition of ABC's "20/20," "Captive: A Journey of Hope and Survival," is airing two years after Berry, Gina DeJesus and Michelle Knight escaped from Castro's house. Featuring the first national broadcast interviews with Berry and DeJesus, it's also airing a day after the release of their memoir, "Hope: A Memoir of Survival in Cleveland," written with Pulitzer Prize-winning Washington Post journalists Mary Jordan and Kevin Sullivan.

Knight was the first of three Cleveland women abducted by Castro. She disappeared in August 2002. She was 21 at the time.

Knight, Berry and DeJesus were held captive by Castro for more than 10 years. Berry was kidnapped in April 2003, the day before her 17th birthday. DeJesus was 14 when she disappeared in April 2004.

Berry and DeJesus tell Roberts about how Castro lured them into his Seymour Avenue home, what they endured as his prisoners, how they felt about each other and how they escaped.

"At first it was so unreal," Berry tells Roberts. "When the cops had gotten there, I told them, 'There's two other girls in the house.' ... They put me in a car, and then that's when they ran upstairs to get them, and once I saw that, I'm like, 'This is it. I think we're free now.'"

The ABC News interviews were conducted in Cleveland, and Roberts visited the abduction sites with Berry and DeJesus. Portions of the interviews will air Monday and Tuesday on "Good Morning America." Excerpts will also air Tuesday on "World News Tonight with David Muir," "Nightline," ABC News.com, and GoodMorningAmerica.com on Yahoo!

"I did two days with them, interviewing them at a neutral location - a place that was very comfortable and had several different rooms," Roberts said during an interview about the interviews. "Their families and close friends were there with them. We didn't want to do this in New York, in a sterile environment. We wanted to make them as comfortable as possible."

When Roberts got the assignment to interview Berry, now 29, and DeJesus, 25, her first question was, "Are they ready to talk about this?"

"I'm not an interrogator," Roberts said during a telephone interview. "They have to be willing and able and wanting to share this story. And they absolutely were. I can't remember when something like this has happened and it has taken this long for the principals to speak. And I admire them for that. Their health and well-being and re-acclimating themselves to life and their families were priorities."

Roberts also thinks that writing the book helped them prepare for a national interview.

"It helped them to be able to articulate what they wanted to say," Roberts said. "I expected them to still be a little more guarded and shattered and fragile. I just marveled at how strong they both seemed. They've not only survived, but thrived. They're here to live their lives and thrive."

Berry talks to Roberts about her daughter, Jocelyn, being born while she was Castro's prisoner. Jocelyn now is 8 years old. DeJesus says having a little girl with them was a welcome distraction.

"It was fun because I can get away from the situation," DeJesus tells Roberts. "When I was playing with Jocelyn, Jocelyn made me forget everything."

For Roberts, the most surprising moment of the interviews came when she asked Berry about the television they watched during the years of captivity.

"Amanda knew who I was, because she had watched me over the years," Roberts said. "I was moved to tears when Amanda told me that she watched me on television, that she'd seen my struggle with health issues. And she'd seen how I overcame my health issues."

Roberts was diagnosed with breast cancer in 2007. She was diagnosed with myelodysplastic syndrome (MDS), a disease of the bone marrow, in 2012.

"You never know who's watching, and you never know who you're reaching in some way," Roberts said. "This is not about me. What they went through was humongous compared to what I went through. This is totally about their resilience and their strength. I can't imagine enduring what they went through and still have so much hope and still have such a lovely soul."

Still, Roberts believes that Berry's familiarity with her story helped put her at ease and earn her trust.

"I'm touched when people tell me how much my story meant to them, but to hear Amanda Berry say that to me?" Roberts said. "My jaw literally dropped when she said that. I was not prepared for it."

Castro pleaded guilty to more than 900 criminal counts that included kidnapping, rape and aggravated murder. As part of a plea bargain, Castro was sentenced to life imprisonment plus 1,000 years, without the chance of parole.

Castro was found dead on Sept. 3, 2013, hanging by a bedsheet in his cell at the Correctional Reception Center in Orient, south of Columbus.

"He was the devil," Roberts said. "He was so cruel and maniacal, and one of his cruelties was to play them against each other. Ariel Castro was not some mythical monster. He was a real figure sitting in that courtroom at the end. Those girls went through hell for a decade and survived. He couldn't last but a few months in prison and had to take his own life. Good triumphs over evil."

Knight was the first of the three to talk about the brutal years of captivity, appearing on Phil McGraw's syndicated "Dr. Phil" show in November 2013. A year later, on top of the publication of her memoir, "Finding Me: A Decade of Darkness, A Life Reclaimed," she was interviewed by NBC's Savannah Guthrie for "Dateline," CNN's Anderson Cooper and again by McGraw.

"It's interesting that three women can be held in the same home by the same man and have three very different journeys," Roberts said. "Each of the women's journey is different, and I did ask them about their relationship with Michelle. We didn't shy away from that, and they discuss it in the book. There's not much communication with her. But they're respectful of Michelle and where she is in her journey."

Roberts says that one of the most memorable moments of the interview was when Berry and DeJesus talked about watching TV coverage of vigils for them.

"They actually were watching," Roberts said. "I know I've rolled my eyes when a producer has asked me to ask the parent of someone who has been abducted, 'If your child is watching, what would you say to them?' And I'd think, 'Oh, come on. What are they chances they're going to be watching?'

"Well, they were watching. They saw it. It gave them hope and strength. They thought, 'OK, if you're going to keep fighting for me after all of these years, I'm going to keep fighting, too.' "

So Roberts asked Berry. "Look to the camera right now, and if somebody is watching this who is being held against their will, like you were, what do you want to say to them?"

"You'll have to watch to see how she answered," Roberts said. "And it was so powerful coming from her, the way she just looked at the camera and delivered what she wanted to say."

Although the "20/20" special describes the horrors inflicted on Berry, DeJesus and Knight by Castro, it is, Roberts said, ultimately an inspiring hour.

"It's just like the title of their book, survival and hope," she said. "It's not just about the recounting of the horrors of the time, but where are they now? How do you go about healing whatever you've gone through? If we were just doing an hour of recounting the horrors and what they endured, it would be a very limited approach."

Hope is what people want to see, Roberts said: "People need to know that even the darkest circumstances can be overcome. The passions are still there. The passion for life still is there. He could take a decade away from them, but he couldn't take their humanity."